The present invention relates to an etching method of forming circuit patterns, particularly, microcircuit patterns on a printed circuit board.
A conventional etching method for forming microcircuit patterns on a printed circuit board is performed by utilizing an etching solvent of water solution including cupric chloride, ferric chloride, persulfate, and hydrogen peroxide, sulfuric acid and alkali solvent or the like, with the discharge pressure of the etching solvent from the nozzle being made very low, and with the spraying pressure of the etching solvent being 1.about.3 kg/cm.sup.2.
In the above conventional etching method, the printed circuits are formed with a large flow amount of etching liquid, such as a low discharge pressure of 1.about.3 kg/cm.sup.2 and a discharge flow rate of 8.about.10 lt/min. In this case, balance of etching becomes worse on the upper surface of the printed circuit board, resulting in a residue of etching on the upper surface thereof, and an over-etching on the lower surface of the printed circuit board, thereby loosening the printed circuits from the printed circuit board. Therefore, at present, it is difficult to carry out the stable and uniform etching method in case of forming the printed circuits having width of 0.1 mm or less.